Title: Self-Organized Hydrodynamic models for nematic alignment and the application to myxobacteria

Speaker: Hui Yu, YMSC

Time: Sep. 26

Abstract: A continuum model for a population of self-propelled particles interacting through nematic alignment is derived from an individual-based model. The methodology consists of introducing a hydrodynamic scaling of the corresponding mean field kinetic equation. The resulting perturbation problem is solved thanks to the concept of generalized collision invariants. It yields a hyperbolic but non-conservative system of equations for the nematic mean direction of the flow and the densities of particles flowing parallel or antiparallel to this mean direction. An application to myxobacteria is presented.

Title: Coordinate Descent Methods

Speaker: Wotao Yin, UCLA

Time: Sep. 18 (周一下午3:15), Lecture Room 1, Floor 1, Jin Chun Yuan West Building

Abstract: This talk overviews a class of algorithms called coordinate descent algorithms and also discusses its recent progress. This class of algorithms has recently gained popularity due to their effectiveness in solving large-scale optimization problems in machine learning, compressed sensing, and image processing. Coordinate descent algorithms solve optimization problems by successively minimizing along each coordinate, or block of coordinates, which is ideal for parallelized and distributed computing. This talk gives relevant theory and examples about how to effectively apply coordinate descent to modern problems in data science and engineering, how to linearly speed up the algorithm by asynchronous parallel computing, and how to obtain global optimality guarantees from those on each coordinate.